Expressed DNA
by WeirdLittleStories
Summary: Dr. McCoy is grumping again because Spock doesn't act like the half human McCoy knows he is. Nurse Chapel gives him another way to think about the matter, with some help from Kirk and M'Benga. (The automatic software claims that this story features a romantic relationship between Chapel and Kirk, but it does NOT.)


_**Expressed**_** DNA**

Spock exited Sickbay, walking swiftly, his quick stride helping to dissipate the annoyance he wouldn't admit to feeling, after his latest exchange of barbs with Dr. McCoy. Inside Sickbay, Kirk and McCoy watched the doors close behind him, and McCoy turned to Kirk, "Blast it, he's half human! If only he'd act like it."

Kirk opened his mouth to try to make peace, then shut it when he heard Nurse Chapel's voice behind him: "He's not, you know."

McCoy turned irritably to Chapel. "What do you mean, he's not?"

"He's half human only at the very grossest level," she said. "As a doctor, you should know that what's important isn't the percentage of human or Vulcan in his raw DNA but that in his _expressed _DNA, and his Vulcan DNA is overwhelmingly dominant over his human DNA."

"Huh," McCoy said. "I guess it is, at that. The internal arrangement of his organs follows the Vulcan pattern."

"Yes, Doctor," Nurse Chapel said. "And he has an inner eyelid, like Vulcans do. His heart beats 250 times a minute, like a Vulcan's does, not 70 times a minute, like a human's, and his blood pressure is correspondingly low. Like a Vulcan, he has no appendix."

Dr. M'Benga, overhearing the conversation, walked over and joined in. "He goes into healing trances the way a Vulcan does." He glanced at Chapel and smiled. "And has to be brought out of them the way a Vulcan does, no matter how much Scotty objects."

Kirk joined in. "I'm not a medical professional, but I can't count the number of times he's been instrumental in saving this ship because he can withstand more heat or pressure or radiation or whatever than a human could. We _count on _his Vulcan physiology."

"He sleeps as little as a Vulcan, restoring himself mostly through mediation," Chapel said. "And he can go for a week or more without eating, which would have most humans passing out from low blood sugar."

McCoy rubbed his face, remembering a certain experience in the Mirror universe. "He's a telepath, which few humans are, and he does mind melds in the Vulcan way, which even humans who _are_ telepaths don't do."

"And Spock's a lot stronger than any human," Kirk said. "When we've had to subdue him for some reason or another, it takes at least three of us, sometimes four or five. They say that Vulcans are three times as strong as humans, and I can attest that Spock's fully as strong as any Vulcan."

"Plus he has an eidetic memory," M'Benga said. "Some humans have a photographic memory, but it's rare; I'm sure we've all wished for one at some time or another."

Laughter all around. "Oh, yeah!" Kirk said. He sobered. "On the other hand, there are things I've been glad to forget, too, and he ... can't, can he?"

"Humans like to believe that they can multi-task," Nurse Chapel said, "But studies show that we can't, actually. Trying to do two things at once reduces performance on both tasks. But Vulcans can carry on a conversation with you while performing complex calculations in their heads at the same time. And we've all seen Spock do that."

"I can vouch for his Vulcan hearing," McCoy said. "He's heard me at times I'd rather he hadn't."

Kirk smiled at him, remembering their interaction on the Bridge after Spock had recovered his sight after the parasite infestation on Deneva. "And his reflexes are as fast as a Vulcan's," he added, remembering being pushed out of the way of a flower shooting poison darts on Gamma Trianguli VI.

"He went into _pon farr _like a Vulcan," Nurse Chapel said, "Even though he was actually _hoping_ for his human side to be dominant for once." She chuckled nervously.

"When you all were aging rapidly after visiting Gamma Hydra IV, Spock aged as slowly as a Vulcan," M'Benga offered. "We know that he's mostly Vulcan culturally, and he really does seem to be almost entirely Vulcan, physiologically."

"I might have an actual number," Nurse Chapel said.

"Really?" McCoy said. "What number?"

"You remember when you operated on Ambassador Sarek, and Spock donated blood," she said.

"Of course."

"His blood was mostly Vulcan, with a few human factors that had to be filtered out before we could give that blood to his father."

"And you were in charge of the filtering," McCoy said, catching on. "How much of his blood was Vulcan?"

"87.6%," Nurse Chapel said.

"So only 12.4% of his blood was human?"

"Yes. And if you think about his physiology as a whole, that number seems like a fairly accurate figure."

"12.4% human," Kirk said. "What's that in fractions — one-eighth?"

"Yes," Chapel said. "So it might be more accurate to say that Mr. Spock is one-eighth human." She looked down. "We might all have different expectations of him if we thought of him as one-eighth human." She looked back up and met Kirk's eyes.

"Some of us might not expect him to fall in love with us if we thought he was only one-eighth human," Kirk said, and Chapel blushed, thinking that Kirk was talking about her, with her notorious crush on Spock. Kirk's eyes were distant, though, and his expression sad. "One-eighth," he repeated, as if wondering if that might be enough for some purpose of his own...

.

* * *

Notes:

1. I'm not a biologist, and the mechanisms for gene expression are far, FAR more complicated than anything I could put into this story. Nurse Chapel's rough-and-ready calculation is used for story purposes and is not meant to represent actual practice. :-)

2. I usually think in the TOS universe, but this probably works in the Reboot universe, too, assuming that the Reboot guys go on to experience some of the same events.

3. I wrote this story because characters in TOS keep talking about how Spock is half-human, yet nearly everything we know about his anatomy and physiology says that he's almost pure Vulcan. I thought that at least ONE of the TOS characters should think about the implications of that, and since Chapel is both a medical professional and a person who has a crush on Spock, it seemed likely that she'd have given the most thought to this. ;-)

4. I don't even pretend to own Star Trek; if I did, TOS would never have gone off the air, Theodore Sturgeon and Dorothy Fontana would have written more episodes, and Gene Coon would never have left. :-)


End file.
